This invention relates to coated abrasive materials commonly used to smooth and polish a wide variety of materials including, for example, those made of wood, metal, plastic and glass. Coated abrasives may also be employed during manufacturing processes to shape and form a work piece, or to roughen and texture a work surface.
For example, coated adhesive materials are used in microfinishing apparatus such as that produced by Industrial Metal Products Corporation and disclosed in Judge et al., U.S. Pat. No. 4,682,444. This device has application in size control and is used among other things, for high tolerance shaping and polishing of engine crankshafts, camshafts and power transmission shafts.
As shown in Judge et al. (See also FIGS. 1 and 2 herein), a microfinishing device typically includes a polishing shoe assembly mounted on a moveable arm. A coated abrasive tape is threaded through the shoe and is held in compressive engagement against a segment of the work piece by rigid or flexible polishing shoe inserts. The work piece is then flooded with a liquid coolant and rotated in one or more directions. At the same time, the polishing shoe may be oscillated from side to side on the work surface. Each time the machine cycles to begin on a new operation, a portion of the coated abrasive tape is advanced to replace a portion of the previously used tape with a fresh, unused abrasive surface.
Several different operations may be accomplished using the above-described device. For example, in one stage, a freshly milled work piece may be treated with relatively coarse abrasive materials to bring the work piece into compliance with its design specifications, reduce irregularities in the work surface and otherwise reshape the work surface. In an additional stage, the work surface may be contacted with a very fine coated abrasive to polish and smooth the work surface and to eliminate any remaining marks or irregularities.
Various factors, such as the stability, movement and surface condition of the coated abrasive tape, as well as the shape and condition of the polishing shoe inserts, affect the success of this finishing process. In each of the above stages, the coated abrasive must be held firmly and securely in proper alignment with the work surface to ensure that the dimensions of the work piece are formed or maintained accurately and according to specification.
Any changes in the surface condition or geometry of the coated abrasive tape will adversely affect the microfinishing operation. In particular, if the coated abrasive tape or the polishing shoe inserts are out of alignment or contain irregularities such as bumps, grooves, ridges and the like, these misalignment and irregularities will create corresponding defects in the work surface. Such misalignments or irregularities may be caused, for example, by slippage of the coated abrasive tape, worn or misshapen polishing shoe surfaces, accumulated debris on the polishing shoe inserts, deformation of the abrasive tape, and debris falling between the face of the coated abrasive tape and the work piece.
These concerns, moreover, are not limited solely to microfinishing devices. In many applications, particularly those involving precise tolerances, coated abrasives should not possess undesirable irregularities and must be held firmly and securely in place to ensure the proper action of the coated abrasive without injury to the work surface. This is especially true where coated abrasives are exposed to adverse pressures, shear forces, frictional forces and temperatures, or where liquid coolants and the like may interfere with the securement and orientation of the coated abrasive.